Bricksafe URL

Location

Interests

Favourite Set(s)

Question: has anyone been able to use the v3 user POST "sync" API on the Swagger page?
The API in question (third from the bottom):
/api/v3/users/{user_token}/sets/sync/
When I test it with a valid user token, passing valid entries for each field as well as a primary build set number (meaning, someSetNum-1) I get a consistent 404 response code. I have not tried calling into it with actual code, strictly trying to get the Swagger implementation to work first. I do not have any issues with any of the other APIs, no matter the verb.
Any help / insight will be appreciated!